A conventional example of a linear guide apparatus is shown in FIG. 11. This linear guide apparatus includes a guide rail 100, a slider (also referred to as “bearing”) 200, and a plurality of rollers (rolling elements) 300. The guide rail 100 and the slider 200 are disposed so as to face with each other to have therebetween rolling surfaces 110 and 210, respectively, which form a rolling channel for the rollers 300.
The slider 200 can be divided into a slider main body 201, end caps 202 attached to both ends of the slider main body, and side seals 203 further attached to both ends of the slider main body in the lengthwise direction of the guide rail 100. The rolling surfaces 210 are formed in the slider main body 201. The side seals 203 disposed at both ends in the linear-motion direction of the slider 102 have lips that seal spaces between the slider 200 and the top face of the guide rail 100 and between the slider and both side faces of the guide rail 100.
The slider 200 also has return channels 221 for the rollers 300 and turn-over channels 222 which cause respective return channels 221 and respective rolling channels to be communicated with each other. The return channels 221 are formed in the slider main body 201 and the turn-over channels 222 are formed in each end cap 202. Female screws 205 which enable attachment of a table, etc., by means of screws are formed on the top face of the slider 200.
Attachment holes for a grease nipple 400 are formed in the side seals 203 and the end caps 202. A lubricant is introduced to an oil path of the end cap 202 through the grease nipple 400, and thus the linear guide apparatus is lubricated. The side seals 203 and the end caps 202 are attached to the slider main body 201 by bolts 500. Attachment holes 120 for enabling attachment of the guide rail 100 to a mounting object like a base by means of bolts are formed in the guide rail 100.
According to this linear guide apparatus, a circulation channel for the rolling elements is formed by the rolling channel, the return channel, and the turn-over channel, and the rollers 300 circulate in the circulation channel, thereby allowing one of the guide rail 100 and the slider 200 to take a linear motion with respect to the other.
An example conventional side seal for such a linear guide apparatus has a metal plate and abase for a rubber-made seal member fixed on the metal holder plate, and brings the lip of the seal member into contact with the top face of the guide rail and both side faces thereof when in use.
Patent Document 1 discloses a technology that the holder plate (a casing) for the side seal and the seal member (a seal) with a lip (a sealing lip) are formed of different members, and a scraper is disposed so as to face the external face of the guide rail with a clearance from such an external face at the opposite side of the holder plate for the seal member. The holder plate and the seal are engaged with each other by fitting of a protrusion and a recess. According to such a side seal, relatively large foreign materials are repelled by the scraper at first, and thus the sealing lip can have a longer life and an improved action.